This invention relates to amphibious transporters capable of movement on land, and in particular relates to walking vehicles which travel over land or over marshy areas by walking action on a pair of pontoon-like members supporting stable on-deck structures that move forward or backward at a constant rate of travel.
Such amphibious transporters or walking vehicles are constructed to have a pair of pontoons which are successively moved ahead by a walking action for use on land or over marshy areas and which may also operate as a watercraft by means of a conventional propeller and rudder at the stern of the vehicle. The problem of walking has been solved by nature in man and many other animals by providing at least two supports such as legs which are lifted alternately and advanced for going forward or reversed if backward movement is desired. The upper half of the body is supported by the legs and is relatively stationary to the ground at all times during walking, while one leg alternately bears the body weight which is shifted as each leg and foot is moved for each step either forward or backward. The weight associated with the supporting structure (the legs) which is lifted and moved forward or backward with each step moves steadily forward or backward in a more or less level plane without a noticeable lift or variation in the rate of travel. Speeding up the rate of travel beyond a certain amount, the walking speed passes into a phase of travel which is termed running. This type of motion is a completely different system of motion than walking. In this type of motion during movement of one support (the leg and foot) the other support is off the ground. That is, both supports for a short part of the movement cycle, depending upon the speed, will be off the ground. This results in the main body portion moving forward in a series of waves or undulations without a substantial shift of weight from one support to the other. Thus, movement of the body or mechanical structure of large size must necessarily be restricted to a walking action in order to maintain stability.
The object then is to search for and realize a walking device or mechanism which incorporates the design of a normal walking action during which relatively lightweight supports are alternately lifted and moved either forward or backward, as desired, while the main weight of the structure or body moves forward or backward uniformly and steadily or constantly in a level plane. The speed at which the movement can be attained is necessarily limited as in nature.
In order to produce an effective mechanism it is important that certain rules should be followed. Among these are that the weight of the body to be moved should be kept to a minimum. Also, the length of each step should be made as long as practical in order to reduce such steps and the number of lifts or transfers of weight in any given distance. Thirdly, the height of the lift of the supports should be made as small as is compatible with the type of terrain to be traversed. With the use of a floating bearing and bushing, the height of each step can be made adjustable. Lastly, as it requires power to accelerate the supports which increases as cube of speed practicalities dictate the speed of the walking action be limited to a reasonable amount. A conservative speed would be from four to six miles per hour.
In order to meet the requirements set forth above, the vehicle disclosed herein is designed with all of the payload and as much as possible of the structural weight and auxiliary equipment be carried or concentrated in the upper platforms or body and superstructure and not in the supports. The upper portion or body is to be relatively free from the action of the supports and allowed to move forward or rearward at a uniform rate of travel at a constant level condition. For purposes of balance it is necessary to construct a device with three supports or feet, the center support having a ground-bearing area equal to or nearly equal to the ground-bearing area of the two outside feet. These supports which are designed and used as pontoons, alternately act as a stable roadway for the upper platform to roll on at all times. The supports are reduced to the absolute minimum in weight and a maximum in bearing area with the height of step or lift being preferably adjustable while underway by the operator of the transporter. Since the device is amphibious, the feet or pontoons are constructed to provide buoyancy and may be controlled by a pumping system in order to control the depth to which the unit will operate. Also, by sloping the forward and aft bows and adding grousers over portions of the supports, the transporter will have the ability to surmount obstacles or crush obstacles so they can be passed over. A number of power systems are suitable and can be incorporated into the transporter. The power system can be diesel or mechanical, which may impose very high pressures on gear teeth bearings and drive chains or diesel-electric which is preferred in view of the need to master heavy forces and slow speeds. The latter combination would provide the flexibility which could be obtainable through electric controls strategically located.
The necessity of transporting personnel and equipment over a variety of terrain and water dictates the need for improved equipment, especially having off-the-road vehicle mobility. Such vehicles can be of great use in excavations, cultivation of new lands, and other construction work, such as building canals. One such device is disclosed in U.S. Pat. No. 2,667,937, issued Feb. 2, 1954, to the same inventor of the vehicle disclosed herein. There were several disadvantages with this device, including the fact that the deck was not stable and was moved with a pair of the pontoons. Further, the original device disclosed in the above-identified patent was not easily turned when used in its land mode. It would be much more desirable if a device could be constructed which could be easily turned and have a stable level platform for working on.